A prosecutor told jurors in opening statements Monday that George Zimmerman fatally shot Trayvon Martin “because he wanted to,” not because he had to, while the neighborhood watch volunteer’s attorney said the deadly shooting of the Miami-area teen was carried out in self-defense.

The opposing attorneys squared off on the first day of testimony in a trial that has attracted international attention and prompted nationwide debates about gun control, race, and equal justice under the law.

Trayvon Martin, 17, was killed by George Zimmerman in Sanford, Fla. on Feb. 26, 2012, as he returned from a trip to a local 7-Eleven. (Martin family photo)

Included among the millions likely to be following the case are civil rights leaders the Revs. Jesse Jackson and Al Sharpton, who joined national protests in the weeks before prosecutors filed second-degree murder charges against Zimmerman 44 days after the shooting.

Zimmerman, who identifies himself as Hispanic, has denied that the shooting had anything to do with race. His mother was born in Peru. His father is a white American. Martin was black.

Prosecutor John Guy’s first words to jurors recounted what Zimmerman told a police dispatcher in a call shortly before the fatal confrontation with Martin: “F—— punks. These a——-. They always get away.”

Zimmerman was profiling Martin as he followed him through the gated community where Zimmerman lived and Martin was visiting, Guy said. He said Zimmerman viewed the teen “as someone about to a commit a crime in his neighborhood.”

“And he acted on it. That’s why we’re here,” the prosecutor said.

Zimmerman didn’t have to shoot Martin, Guy said.

“He shot him for the worst of all reasons: because he wanted to,” he said.

Defense attorney Don West told jurors that Zimmerman was being viciously attacked when he shot Martin. Zimmerman was sucker-punched by Martin, who then pounded Zimmerman’s head into the concrete sidewalk, West said. He played for jurors the call to a police dispatcher in which Zimmerman used the obscenities.

Martin had opportunities to go home after Zimmerman followed him and then lost track of him, West said, but instead the teen confronted the neighborhood watch volunteer.

“I think the evidence will show that this is a sad case,” West said. “There are no monsters here.”

The prosecutor described Zimmerman as someone who wanted to be a police officer, and he dismantled the story Zimmerman has told investigators about what happened during the fight between the neighborhood watch volunteer and the Miami-area teen that left Martin dead from a bullet to his chest.

Zimmerman’s claim that Martin had his hands over the neighborhood watch volunteer’s mouth is false since none of Zimmerman’s DNA was found on Martin’s body, Guy said. The prosecutor also said Zimmerman’s claim that he had to fire because Martin was reaching for his firearm is false since none of Martin’s DNA was on the gun or holster.

Zimmerman is pleading not guilty to second-degree murder, claiming self-defense.

On Feb. 26, 2012, Zimmerman spotted Martin, whom he did not recognize, walking in the gated townhome community where Zimmerman and the fiancee of Martin’s father lived. There had been a rash of recent break-ins and Zimmerman was wary of strangers walking through the complex.

The two eventually got into a struggle and Zimmerman shot Martin in the chest with his 9mm handgun. He was charged 44 days after the shooting, only after a special prosecutor was appointed to review the case and after protests. The delay in the arrest prompted protests nationwide.

Two police dispatch phone calls will be important evidence for both sides’ cases.

The first is a call Zimmerman made to a nonemergency police dispatcher, who told him he didn’t need to be following Martin.

The second 911 call captures screams from the confrontation between Zimmerman and Martin. Martin’s parents said the screams are from their son while Zimmerman’s father contends they belong to his son.

Nelson ruled last weekend that audio experts for the prosecution won’t be able to testify that the screams belong to Martin, saying the methods the experts used were unreliable.

Opening statements were made two weeks after jury selection began. Attorneys picked six jurors and four alternates after quizzing the jury pool questions about how much they knew about the case and their views on guns and self-defense.

West noted the difficulty in picking a jury with a joke he told jurors during opening statements.

“Knock. Knock. Who is there?” West said. “George Zimmerman. George Zimmerman who? Ah, good. You’re on the jury.”